A Novel Damage Intensity Index for Tea Mosquito Bug Helopeltis spp. Infestation in Cocoa
DOI:
https://doi.org/10.55446/IJE.2023.1555Keywords:
Decision making tool, tea mosquito bug, Helopeltis spp., Miridae, damage intensity index, cocoa, diameter, regression, sample size, indexing, feeding lesions, gradingAbstract
The present investigation focused on the development of a new damage intensity index (DII) for the tea mosquito bug Helopeltis spp. (TMB) infestation in cocoa. The new DII was developed based on observable symptoms and the intensity of damage, such as the number and diameter of feeding lesions, and TMB-infested areas on cocoa pods. Statistical techniques, including linear correlation and regression, have been employed to develop an appropriate DII. The study reveals a significant correlation between the mean of total feeding lesions (Xn) and feeding lesions present on the middle portion (Xm) of cocoa pods, surpassing other combinations and indicating a strong relationship between these variables. The damage intensity was estimated using a linear regression approach resulting equation, Xn = 1.79 + 0.25Mn (R2 = 0.989), offers a quantified means of estimating damage intensity on cocoa pods. Analysis of infestation and the regression equation establishes DII values between 1.79 to 76.79. This novel index suggests that the minimum sample size of 90 pods is required for estimating a population with a 95% confidence level to arrive at precision decision making of TMB damage on cocoa pods. The novel damage intensity index and the calculated sample size from this investigation could be useful in conducting various studies, such as germplasm screening, breeding for pest resistance, evaluating the effectiveness of new insecticides, and formulating an IPM package for managing Helopeltis spp. in cocoa.
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Alagar M, Bhat K. 2017. Comparison of biology of tea mosquito bug, Helopeltis bradyi Waterhouse (Hemiptera: Miridae) on different phenological stages of cocoa (Theobroma cacao L.). Journal of Plantation Crops 45(3): 155-161. DOI: https://doi.org/10.25081/jpc.2017.v45.i3.3339
Ambika B,Abraham C C, Vidyadharan K K. 1979. Relative susceptibility of cashew types to infestation by Helopeltis antonii Sign. (Heteroptera: Miridae) In: Proceedings of PLACROSYM II; 26–29 June 1979, Ootacamund, India. pp. 513-516.
CPCRI. 1993. Annual report, Central Plantation Crops Research Institute, Kasaragod, Kerala, India. pp. 82-83.
Devasahayam S. 1985. Seasonal biology of tea mosquito bug Helopeltis antonii Signoret (Heteroptera: Miridae): a pest of cashew. Journal of Plantation Crops 13: 145-147.
Entwistle P F. 1972. Pests of Cocoa. Tropical Science Series. Longman, London, UK. 779 pp.
Mahapatro G K. 2008. A refined damage rate scoring method for tea mosquito bug infestation in cashew. Indian Journal of Entomology 70(3): 273-277.
Padi B. 1997 Prospects for the control of cocoa capsids – alternatives to chemical control. In: Proceedings First International Cocoa Pests and Diseases Seminar, Accra, Ghana, 6-10 November, 1997. pp. 28-36.
Thube S H, Mahapatro G K, Mohan C, Pandian R T P, Apshara E, Jose C T. 2019. Biology, feeding and oviposition preference of Helopeltis theivora, with notes on the differential distribution of species of the tea mosquito bug species complex across elevations. Animal Biology 70(1): 67-79. DOI: https://doi.org/10.1163/15707563-20191083
Thube S H, Pandian R T P, Babu M, Josephrajkumar A, Mhatre P H, Kumar P S, Nirmal Kumar B J, Hegde V, Chavan S N. 2022a. Evaluation of a native isolate of Metarhizium anisopliae (Metschn.) Sorokin TMBMA1 against tea mosquito bug, Helopeltis theivora infesting cocoa (Theobroma cacao L.). Biological Control 170: 104909. https://doi.org/10.1016/j.biocontrol.2022.104909. DOI: https://doi.org/10.1016/j.biocontrol.2022.104909
Thube S H, Pandian R T P, Josephrajkumar A, Bhavishya A, Kumar B N, Firake D M, Shah V, Madhu T N, Ruzzier E. 2022b. Xylosandrus crassiusculus (Motschulsky) on Cocoa Pods (Theobroma cacao L.): Matter of Bugs and Fungi. Insects 13(9): 809. https://doi.org/10.3390/insects13090809. DOI: https://doi.org/10.3390/insects13090809